1. Field of the Invention
The present invention relates to supports for an image-recording material which have better density, elasticity modulus, tensile strength, strength, and the like; which are excellent in dimension stability and smoothness; and with which curling is less likely to occur, compared with conventional supports. The present invention also relates to processes for manufacturing such supports for an image-recording material and to image-recording materials using such supports thereby being capable of forming high quality images.
2. Description of the Related Art
Conventionally, in a process of fast and efficient papermaking, a sheet of paper is dried as it passes through a number of cylindrical driers while being tensioned in a vertical direction (the direction of papermaking) and contracting freely in a horizontal direction. Accordingly, when such a sheet of paper is subjected to a change of humidity, it tends to contract or expand largely in the horizontal direction. Therefore, when the sheet of paper is used as a support and information is recorded for example in a form of a photograph, curling occurs and provides a disadvantage of not being able to obtain a high quality image.
To solve this issue, transfer paper for electrophotography proposed in Japanese Patent Application Laid-Open (JP-A) No. 01-292354 (Japanese Patent (JP-B) No. 2739160) is manufactured using a so-called Yankee paper machine which does not tension in the vertical direction during the drying process and can restrict the drying contraction in both vertical and horizontal directions so that even if the transfer sheet is subjected to a humidity change after it is dried, the rate of contraction is small, its smoothness is excellent, and a degree of curling is small.
However, when a sheet of paper is manufactured using a Yankee paper machine as in JP-A No. 01-292354, the freeness of pulp is generally limited to a range of from 400 ml to 600 ml Canadian Standard Freeness (C.S.F.) and many other papermaking conditions such as papermaking speed are limited, resulting in very strict limitation on manufacturing.
On the other hand, a treatment in which a sheet of paper is dried while being pressurized (hereinafter may be referred to as pressure drying treatment or press dry treatment) is expected to provide higher strength, elasticity modulus, density and the like, and such process is currently under development (T. Kadoya et al., Seishi Kagaku [Science of papermaking] (Tokyo: Chugai Sangyo Chosakai, 1982), pp. 174-177). In addition, JP-A Nos. 2000-500536 and 07-91829 (JP-B No. 3041754) propose web pressure drying apparatuses which perform thermal drying of a fiber web with a press dry treatment and provide less limitations when used in a manufacturing line.
However, Seishi Kagaku does not disclose nor suggest specific conditions or the like for a press dry treatment. Moreover, JP-A Nos. 2000-500536 and 07-91829 only disclose press dry apparatuses and they do not disclose nor suggest a relationship between a press dry treatment and a support for an image-recording material. Therefore it is difficult to predict that a press dry treatment is applicable to a support for an image-recording material and that a high quality image can be formed.